If the laptop does not overheat under load, then you should be delighted. Less fan at idle means lower noise and slower accumulation of dust so less maintenance.
Normally, Dell laptop BIOS updates make things louder, to try to reduce RMA issues after some unexpected overheating problems are found after release. In the most egregious example, they turned the fans on G84 and G86 equipped laptops to full blast all of the time after
all of them turned out to be defective, in hopes of delaying the onset of the problem until they were just out of warranty.